When he grows out of it I guess.
My oldest son wore a Snow White costume (no, I'm not kidding, he had a Snow White dress) pretty much everywhere for about a year, then, one day when he was 4 he just decided that he didn't want to be Snow White anymore... then I made the mistake of buying him a Batman costume for his 5th birthday and suddenly I had Batman following me around everywhere, that one only lasted about 6 months... then came the Power Ranger costume.
In short, he's 18, he wears normal clothes now, they get over it eventually.
